Excluding Zeros in Min function

I have a formula field that contains numbers and zeros and groupings.  If I have 0,25,50,100 as data points, I want to be able to use a min function to pull the minimum number excluding Zero for each group...so in this case it would pull 25 as the min. for group 1.  I tried using running total but that still pulls zeros or ""

What is the cleanest and most direct way to accomplish this, other than eliminating zeros via record selection?...i need all records returned to the report b/c I need to perform different calculations on the same data.

Thanks!